In the course of treating and preparing subterranean wells for production, a well packer and screen along with a service tool are run into the well on a work string, with the packer being releasably anchored against a casing bore.
It is necessary to manipulate the service tool within the well to set, position or release the packer. The success of such operations is dependent upon the ability to reciprocate the tool vertically and/or rotate it relative to the packer. Rotational displacement of the tool in some wells, for example in deviated wells, is difficult to perform reliably because of frictional binding between the work string and the well casing.
During run-in, the packer is mechanically locked in the unset condition by shear pins to prevent premature setting. It is essential that the packer remain in the unset condition while withstanding run-in forces caused by jarring, torquing and compression/tension loading as the packer is forced through tight bends, for example in deviated bores and in horizontal completions. Moreover, it is desirable that the packer be retrievable from the well by appropriate manipulation of the tubing string and tool to cause the packer to be released and unsealed from the well bore. In some installations, the packer may be released from set engagement by a straight pull upwardly on the work string, or by rotation of the work string, or by a combination of straight pull and rotation operations.